First pass on compatibility tests

With some help from GPT, add a TCL script that has similar syntax as
some of the SQLite source tree tests.

testing/all.test

@@ -0,0 +1,31 @@
+#!/usr/bin/env tclsh
+
+set sqlite_exec [expr {[info exists env(SQLITE_EXEC)] ? $env(SQLITE_EXEC) : "sqlite3"}]
+
+proc evaluate_sql {sqlite_exec sql} {
+    set command [list $sqlite_exec database.db $sql]
+    set output [exec {*}$command]
+    return $output
+}
+
+proc run_test {sqlite_exec sql expected_output} {
+    set actual_output [evaluate_sql $sqlite_exec $sql]
+    if {$actual_output ne $expected_output} {
+        puts "Test passed: '$sql' returned '$actual_output'"
+    }
+}
+
+proc do_execsql_test {test_name sql_statements expected_outputs} {
+    puts "Running test: $test_name"
+    set combined_sql [join $sql_statements " "]
+    set combined_expected_output [join $expected_outputs "\n"]
+    run_test $::sqlite_exec $combined_sql $combined_expected_output
+}
+
+do_execsql_test select-1 {
+  SELECT 1
+} {1}
+
+do_execsql_test select-2 {
+  SELECT 2
+} {2}